Trout Quintet

The first movement is in sonata form. As is commonplace in works of the Classical genre, the exposition shifts from tonic to dominant; however, Schubert's harmonic language is innovative, incorporating many mediants and submediants. This is evident from almost the beginning of the piece: after stating the tonic for ten bars, the harmony shifts abruptly into F major (the flatted submediant) in the eleventh bar.

The development section starts with a similar abrupt shift, from E major (at the end of the exposition) to C major. Harmonic movement is slow at first, but becomes quicker; towards the return of the first theme, the harmony modulates in ascending half tones.

The recapitulation begins in the subdominant, making any modulatory changes in the transition to the second theme unnecessary, a frequent phenomenon in early sonata form movements written by Schubert.[1] It differs from the exposition only in omitting the opening bars and another short section, before the closing theme.

This movement is composed of two symmetrical sections, the second being a transposed version of the first, except for some differences of modulation which allow the movement to end in the same key in which it began. Tonal layout (with some intermediate keys of lower structural significance omitted) as follows:

F major – F♯ minor – D major – G major – G minor – G major; A♭ major – A minor – F major – F minor – F major

This movement also contains mediant tonalities, such as the ending of the first section of the Scherzo proper, which is in C major, the flattened mediant, or the relative major of the parallel minor (A minor).

The fourth movement is a theme and variations on Schubert's Lied "Die Forelle". As typical of some other variation movements by Schubert (in contrast to Beethoven's style),[4] the variations do not transform the original theme into new thematic material; rather, they concentrate on melodic decoration and changes of mood. In each of the first few variations, the main theme is played by a different instrument or group. In the fifth variation, Schubert begins in the flat submediant (B♭ major), and creates a series of modulations eventually leading back to the movement's main key, at the beginning of the final sixth variation.

A similar process is heard in three of Schubert's later compositions: the Octet in F major, D. 803 (fourth movement); the Piano Sonata in A minor, D. 845 (second movement); and the Impromptu in B♭ major, D. 935 No. 3. The concluding variation is similar to the original Lied, sharing the same characteristic accompaniment in the piano.

The Finale is in two symmetrical sections, like the second movement. However, the movement differs from the second movement in the absence of unusual chromaticism, and in the second section being an exact transposition of the first (except for some changes of octave register). A repeat sign is written for the first section: if one adheres meticulously to the score, the movement consists of three lengthy, almost identical repeats of the same musical material. Performers sometimes choose to omit the repeat of the first section when playing.

Although this movement lacks the chromaticism of the second movement, its own harmonic design is also innovative: the first section ends in D major, the subdominant. This is contradictory to the aesthetics of the Classical musical style, in which the first major harmonic event in a musical piece or movement, is the shift from tonic to dominant (or, more rarely, to mediant or submediant – but never to the subdominant).[5][6]